1. Field of the Invention
The invention relates to a power tool and more particularly, to a motor support structure of a power tool.
2. Description of the Related Art
Japanese non-examined laid-open Patent Publication No. 2004-106136 discloses an electric hammer drill used for drilling a workpiece such as a concrete. In the known electric hammer drill, a motor for driving a drill bit is disposed in the tip end (front end) region of the hammer drill and housed within a motor housing such that axial direction of the motor is parallel to the axial direction of the drill bit. A front portion on the tool bit side and a rear portion on the grip side of a rotating shaft of the motor are rotatably supported by respective bearings. A grip side bearing housing for housing the rear grip side bearing extends toward the grip and is covered by a grip cover disposed on the rear end portion of the motor housing.
According to the known art, the grip side bearing housing for the rear bearing extends toward the grip, the extending end of the grip side bearing housing is free and as a result, vibration may be caused in the free end when the motor is driven. As a measure against such vibration, it is conceivable for example to provide an enforcing rib extending from the rear wall of the motor housing in order to increase the rigidity of the grip side bearing housing. However, on the other hand, the known hammer drill generally has a ring-like member operated by a user of the hammer drill to change the direction of rotation of the motor and such ring-like member is generally disposed in the outer peripheral region of the grip side bearing housing. Therefore, due to the ring-like member on the peripheral region of the grip side bearing housing, the enforcing rib cannot be provided as a measure to increase the rigidity of the grip side bearing housing.